This invention relates to control valves, and in particular, it relates to control valves for controlling the flow of fluid in response to the temperature of said fluid.
In many applications it is desirable or necessary to restrict the flow of fluid when the temperature thereof exceeds or falls below a certain predetermined value. For example, in a residential shower system it is advantageous to restrict the flow of water through the shower head to the point that water is no longer sprayed onto the person taking a shower whenever the temperature of the water entering the shower head becomes so hot as to cause discomfort, scalding or burning of the person taking the shower. The sudden increase of the water temperature can occur whenever the flow of cold but not hot water into the shower system is for any reason prevented or restricted. For example, a rapid discharge of cold water caused by flushing a toilet might cause the cold water pressure to drop momentarily thereby causing a sudden increase of the temperature of water sprayed from the shower head. Similarly, a malfunction in the water supply system or of the mixing valve can result in a sudden increase of the water temperature. The dangers of thermal shock in showers have been recognized by ASTM's committee on Consumer Product Safety which proposed safety specifications for thermal shock preventing devices (ASTM Committee F-15 on Consumer Product Safety Designation F-44).
A number of approaches have been proposed to alleviate the problem of thermal shock and to efficiently control the flow of fluid depending on the temperature of the fluid. None of them has been entirely satisfactory, generally because the systems are expensive, bulky, difficult to maintain and thus have a slow response time. A new approach to the problem is described in a pending patent application of Charles Priesmeyer entitled "Control Valve" (assigned to Mark Controls Corporation), Ser. No. 093,063.
The present invention provides an improved valve for controlling the flow of fluid depending on the temperature thereof, the performance of which valve is not significantly affected by the pressure of the fluid or fluctuations in said pressure. Thus, one object of the invention is to provide an improved control valve for restricting the flow of fluid, which valve contains a minimum number of moving parts, is easy to construct and install, and which operates accurately regardless of the pressure of the fluid or fluctuations in said pressure.
Another object of the invention is to provide a flow restricting valve which is highly reliable, accurate and inexpensive to construct, install and maintain.
A further object of the invention is to provide a control valve which rapidly and consistently responds to the temperature of the fluid passing therethrough and rapidly restricts the flow thereof at a predetermined temperature even when the pressure of the fluid changes or fluctuates.
Still another object of the invention is to provide a restricting valve which in restricted position responds rapidly to the change in the temperature of the incoming fluid and reopens the flow of fluid therethrough.
Other objects of the invention will become apparent to those skilled in the art upon studying this disclosure.